Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import collections
h,w = map(int,input().split())
s=[list(input()) for _ in range(h)]
deq = collections.deque([[0,0,0]])

while deq:
    i,j,k = deq.popleft()
    if not((i in range(h)) and (j in range(w))):
        continue
    if s[i][j] != '.':
        continue
    s[i][j]=k
    if i==h-1 and j == w-1:
        break
    deq.append([i + 1, j, k + 1])
    deq.append([i - 1, j, k + 1])
    deq.append([i, j + 1, k + 1])
    deq.append([i, j - 1, k + 1])
if s[h-1][w-1] == '#'or s[h-1][w-1] =='.':
    print(-1)
else:
    black = sum([y.count('#') for y in s])
    print(h*w-black-s[h-1][w-1]-1)